Use the first method in general and the second method when required.
The example illustrates that there is no single phase centre and that the best phase
centre calculation method depends on the requirements of the application. The phase
centre calculation at a single point (method 1) should be used in general, but the
second phase centre calculation method can increase the low phase variation area in
cases where this is required.
The graph (below) illustrates the phase variation in a single ϕ
cut. We can see that the original far field varied considerably and is not flat at
θ=90°. The first solution method is
perfectly flat at θ=90°, but quickly
deviates from zero when θ is more than 10° from the centre. The second solution method is not as flat as the
first, but the only starts deviating away from zero when θ is
more than 15° away from the centre.
Figure 1. A Cartesian graph of a single ϕ cut of the phase centre
of the horn antenna example.
